'use strict';

function LightenDarkenColor(col, amt) {

    var usePound = false;

    if (col[0] === '#') {
        col = col.slice(1);
        usePound = true;
    }

    var num = parseInt(col,16);

    var r = (num >> 16) + amt;

    if (r > 255) r = 255;
    else if  (r < 0) r = 0;

    var b = ((num >> 8) & 0x00FF) + amt;

    if (b > 255) {
      b = 255;
    }
    else if  (b < 0) {
      b = 0;
    }

    var g = (num & 0x0000FF) + amt;

    if (g > 255) {
      g = 255;
    }
    else if (g < 0) {
      g = 0;
    }

    return (usePound?'#':'') + (g | (b << 8) | (r << 16)).toString(16);

}
